This application is based on and claims the priority under 35 U.S.C. xc2xa7119 of German Patent Application 100 57 208.1, filed on Nov. 17, 2000, the entire disclosure of which is incorporated herein by reference.
The invention relates to a seat, and especially a passenger seat with an adjustably reclinable backrest, including a seat bottom with a seat frame and a backrest with a backrest frame connected to the seat bottom. In general in this application, the term xe2x80x9cseatxe2x80x9d applies to any seat, chair, couch, recliner, sleeper seat, chaise longue, lounge chair, or the like on which a person may sit, recline, lie, or otherwise rest.
German Patent 198 28 254 discloses a seat arrangement having a backrest including a backrest frame adjustably connected to a seat bottom including a seat frame. This known seat arrangement is intended to provide an anatomically improved support for a person sitting thereon, and is to be adaptable to the seated stature and position of the body of the seated person. To achieve these features, the known seat arrangement includes a base member of a corrugated sheet of spring metal, of which the corrugation extends in the longitudinal direction of the seat, and which is stiff in a crosswise direction, but flexible in a lengthwise direction. The base member, which is stiff crosswise and flexible lengthwise, is hangingly supported in a carrier frame, and is adjusted or adapted corresponding to the individual seating desires of the person seated on the seat arrangement. In other words, in response to varying seated positions or postures, the base member moves or repositions itself corresponding to the respective seating position or posture.
Thus, it is known from the above German Patent reference, to provide a possible adaptation to various seated postures or positions by means of the springy element used as a base member. However, the known seat arrangement does not provide an adjustment or adaptability of the spring cushioning or support firmness of the seat bottom responsive and corresponding to a seated condition or a lying condition of the person resting on the seat.
When a person is seated relatively upright on a seat arrangement, the entire body weight of the person is distributed and supported on a relatively small support surface. On the other hand, when a seat arrangement is reclined and a person reclines or lies on the reclined seat arrangement, then the person""s body weight is distributed over a relatively much larger support surface area. Thus, for a relatively upright seat configuration, the spring support or cushioning of the seat bottom surface must be correspondingly harder, firmer or stiffer than for a reclined or lying configuration of the seat arrangement, to provide a comfortable support in both configurations.
If a reclinable passenger seat is equipped to provide a reclined lying function, yet has a seat bottom cushioning that is relatively hard and adapted to provide a proper support for a sitting passenger, then it may be uncomfortable for a passenger and lead to back pains or the like, if the passenger lies in a reclined position on the seat for an extended time. On the other hand, if the seat bottom cushion is made relatively softer and thereby adapted to a reclined or lying position of the seat and the passenger, then the ergonomic requirements for proper upright seated support are not met, and the seat may become uncomfortable for the passenger particularly during a long upright seated phase, for example during long distance flights.
In view of the above, it is an object of the invention to provide a seat arrangement having a backrest that is reclinably connected to a seat bottom, for supporting a person sitting, reclining or lying thereon, whereby this seat arrangement is adaptable to provide an optimal comfort both when the person is sitting and when the person is lying on the seat arrangement, and also in view of ergonomic issues. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in a seat arrangement comprising a seat bottom including a seat frame, and a backrest including a backrest frame that is reclinably connected to the seat bottom. Particularly according to the invention, the seat bottom further includes a seat bottom support and cushioning arrangement within the seat frame, and a mechanism for adjusting the cushioning stiffness of the seating surface, from a relatively hard or firm stiffness for when the seat arrangement is in a relatively upright seating configuration, to a relatively soft stiffness for when the seat arrangement is in a reclined configuration.
Advantageously according to the invention, the firmness of the seat surface is optimally adapted to the particular configuration of the seat arrangement that is selected at any time. When the seat arrangement is configured in the normal upright sitting configuration, the seat surface is adjusted to a relatively harder or firmer or stiffer characteristic, to provide proper support over the relatively small support surface area for a person seated on the seat arrangement. On the other hand, when the seat arrangement is configured in the reclined configuration, the seat surface is adjusted to a relatively softer characteristic, so as to provide a comfortable surface for the person to lie on the seat arrangement in the reclined configuration. It is especially advantageous that the adjustment of the seat bottom cushioning and support characteristic in this manner can be achieved without great effort, and preferably in an automatic manner linked responsively to the reclining adjustment of the backrest.